The present invention relates to a method for connecting networks of different types of transmission, in which the user data are transmitted as data packets between two network access units in a packet-transmitting network. The transmission in the network is also based on the transmission of data packets.
The data packets have a packet header which contains the address of a destination and the address of the sender. In addition, there is a data packet body in which the user data are transmitted.
The user data are forwarded connectionlessly by network nodes between the network access units. In this context, connectionlessly refers to the idea that no connection setup phase related to the packets to be transmitted is required for forwarding the data packets and that no switching resources are exclusively reserved for transporting the data packets to be transmitted.
A typical example of a packet-transmitting network in which the data packets are transmitted connectionlessly between the network nodes is the Internet. In the bottom three protocol layers of the so-called OSI (Open System Interconnection) model; i.e., in the physical layer, in the datalink layer and in the network layer, the data are transmitted connectionlessly in the Internet. Connections are only used from the transport layer on, if necessary. For example, the TCP (Transmission Control Protocol) protocol is used. Another protocol for the fifth protocol layer is the RTP (Real Time Protocol) protocol which is used for transmitting real-time data, particularly voice data.
On the other hand, there are the circuit-switched networks in which time channels are combined. An example of such a network is the conventional telephone network. These networks are also called circuit-switched networks because connections are switched through for transmitting data, especially voice data, even at the lower protocol levels. Thus, resources are reserved for each connection in the exchanges.
It is an object of the present invention, therefore, to specify a simple method for connecting a packet-based and connectionlessly transmitting network and a circuit-switched network. In addition, associated units, associated programs and data media and data network messages with these programs are to be specified.